Alternative technology is available in the form of U.S. Pat. No. 1,300,275 issued to Johnson in April, 1919 which reveals a combination of a screw having a single hole eccentric with respect to the axis of the screw and a removable driving key having an eccentric pin adapted to enter the full length of said screw. Unlike the present invention, a hole is exposed relative to the head of the screw.
U.S. Pat. No. 4,569,259 issued to Rubin et al. on Feb. 11, 1986 discloses an automobile wheel cover locking bolt and wrench combination wherein the head of the locking bolt has a plurality of axial slots, or lock impressions, about its periphery which may be spaced in accordance with a preselected code. The wrench socket is provided with a corresponding number of key elements projecting inwardly from the cylindrical wall of the socket, the position of the key elements being in accordance with a matching preselected code. Additionally, the head of the locking bolt has an axial recess and the socket of the wrench has an axial pin adapted to align and fit within the recess of the bolt. All of the recesses are visible from the top plane view of the bolt.
U.S. Pat. No. 2,372,269 issued to Golan on Mar. 27, 1945, relates to a socket wrench and cooperating theft resistant nut with fully extending slots and grooves.
A brake tool disclosed in U.S. Pat. No. 5,003,681 by Schley in 1991 reveals a disc like tool having a pin disposed to engage a depression in the surface of a piston.
An anti-theft apparatus including a screw with an anti-theft safety head is disclosed in U.S. Pat. No. 4,964,773 dated Oct. 23, 1990 issued to Schmidt. The disclosed device is for a screw with an extended head that is arranged and adapted to support a locking device which may freely rotate if not set in a locking position. Thus, the head freely rotates relative to the screw preventing the screw from being removed unless the head is first locked thereto. Unlike the present invention, the head is not removable, but merely rotatable about the screw and the structure disclosed is considerably different.
A patent issued to Burge on Jun. 7, 1977, U.S. Pat. No. 4,027,572 reveals a theft resistant screw fastener with both the tool and the nut having axial recesses which accommodate a dowel arranged and adapted to have one of its ends disposed in the recess of the nut and the other in the recess of the tool.
Some of the drawbacks to these designs are that each teaches fasteners that are more readily removable by theft since indentations which can be easily grasped are exposed. Moreover, none of the foregoing inventions is designed to be theft resistant in a surface recess (i.e. a countersunk borehole sized to accommodate the socket body of the wrench).
The citation of the foregoing publications is not an admission that any particular publication constitutes prior art, or that any publication alone or in conjunction with others, renders unpatentable any pending claim of the present application. None of the cited publications is believed to detract from the patentability of the claimed invention.